Federal law enforcement officials, eager to get a deadly array of toxic drugs known as "bath salts" off the streets, say they are frustrated that bureaucratic politics got in the way of congressional lawmakers drafting a comprehensive ban.

"Bath salts are the worst of the worst of the synthetic drugs," said a law enforcement source familiar with the congressional negotiations. "It makes no sense why they aren't all included in the bill."

The bill in question would add an array of ever evolving synthetic drugs to the federal list of illegal substances, but conspicuously missing are many of the elements used in bath salts. The omission has led some lawmakers to accuse their colleagues, particularly Senate Judiciary Chairman Patrick Leahy, D-Vt., of choosing political expediency over public safety.

The Drug Enforcement Administration recently submitted a list of 41 synthetic drugs it wanted Congress to place on the "Schedule I" list of federally criminalized drugs that already includes heroin, cocaine and meth. Among those were 17 chemicals used to produce bath salts, a stimulant believed to have played a role in a spate of grisly incidents including a May assault in Florida in which an attacker allegedly high on the drug chewed off a homeless man's face.

A conference of House and Senate lawmakers last week agreed to ban just two variants of bath salts, leading cops to wonder why only limited steps were taken.

A bill that was recently passed in the House of Representatives sought to add all 17 bath salt chemicals to the government's list of controlled substances. In the Senate, an amendment to an FDA act listed just two bath salts compounds, MDPV and mephedrone.

When House and Senate negotiators concluded their conference talks this week, they agreed to criminalize 26 synthetic drugs, including those found in synthetic marijuana and the street drugs "K2" and "Spice," but listed only the two bath salts chemicals named in the Senate legislation.

Ironically, and to the consternation of law enforcement officials desperate to get bath salts off the street, those two drugs are already illegal after the DEA put them on an "emergency schedule" list last year.

The DEA has no official statistics on arrests or prosecutions for bath salts, a testament to the drug's rapid popularity and the variety of chemicals that fall under the "bath salts" street label.

Between 2010 and 2011, however, the number of calls to poison control centers nationwide related to bath salts increased from 303 to over 6,000, a more than 1,800 percent increase.

Law enforcement officials contend that including all the known bath salts substances on the schedule will make it easier to prosecute the criminals who import, sell and possess the deadly chemicals. If a drug is on the list of controlled substances, investigations and prosecutions can proceed quickly.

"There are no questions about the drug if it's a controlled substance. We just know it's illegal and can get to work. Already, lots of time is wasted just waiting for lab results to come back," said a DEA official.

Law enforcement officials as well as several congressional staffers not authorized to speak on the record but familiar with the negotiations say Leahy chose not to include the additional 15 bath salt drugs included in the House bill.

Congressional Conference Considered Ban on Bath Salts

"Those 15 got lost because in the conference there was some procedural issue and Leahy didn't want to bother with it," said a Senate staffer.

"Bath salts were in the House bill. And they're not in this one. You'd have to ask Sen. Leahy why that happened," said a staffer for a House Republican.

Leahy did not respond to requests for comment from ABCNews.com, but a Judiciary Committee staffer defended Leahy's decision to put just two of the 17 substances in the final version of the bill, saying "Leahy's focus was to get done what the Senate started. The House bill was out there, but not in a formal way."

He argued that with a bitterly divided Congress, getting consensus on a bill as complex as the FDA Safety and Innovation Act was an accomplishment.

When asked why not criminalize drugs that the DEA says it needs listed to help keep the streets safe, the committee staffer said, "Sen. Leahy has been clear that scheduling controlled substances is not something to be taken lightly."

"It is not without implication to put a whole lot of chemicals on the federal drug schedule," he said. "It means putting more people in jail and makes it harder to seek legitimate uses for these drugs. Leahy is most comfortable sticking with what has been carefully considered."

On background DEA officials were frustrated that the bill did not go far enough, but publically the agency "commended House and Senate negotiators for agreeing on legislation to control 26 synthetic drugs."

The bill also gives the DEA new powers to temporarily declare drugs illegal without going through the lengthy scheduling process to permanently criminalize them. Under the new law the agency can place drugs on a two-year "emergency schedule." Currently, the DEA can only emergency schedule a drug for one year.

In the meantime, one DEA official said, agents will be playing a "game of whack-a-mole," discovering new drugs and trying to classify them fast enough to prosecute offenders.